Blood and Nerve Supply to Abdominal Organs

Question 1

What level does the abdominal aorta bifurcate at?

Into what?

Answer 1

L4

L and R common iliac aa.

Question 2

Why must pregnant women lie on their left side?

If they don’t, what happens?

Answer 2

The IVC is on the right and must not be compressed by the baby

Get numbness in the extremities, etc. (or worse)

Question 3

Abdominal aortic aneurysms

Cause

Most often where?

Answer 3

Dilations of aorta

Plaques (atherosclerosis) weaken the walls

Between renal aa. and bifurcation

Question 4

Aortic dissection

Answer 4

Rupture of the intima of the aorta

Blood pools between the intima and the media

Eventually ruptures and blood gushes out

Big blood clot forms and can be deadly

Question 5

3 unpaired arteries off of abdominal aorta

Answer 5

Celiac trunk
SMA
IMA

Question 6

3 paired arteries to NON GI-structures off aorta

Answer 6

Inf. phrenic aa.
Gonadal aa.
Renal aa.

Question 7

How are GI autonomics generally set up?

Answer 7

Series of plexuses around major arteries that are interconnected and carry both sympathetic and parasympathetic fibers

Question 8

Pre-synaptic sympathetic fibers going to the GI autonomics come from where initially?

Pathway of travel?

Answer 8

Gray matter lateral horns

Ganglia here –> roots –> rami –> rami communicants –> thoracic/lumbar spinal nn. –> sympathetic trunks

Question 9

Do pre-synaptic sympathetic nerves to the GI tract synapse in the sympathetic trunks?

What happens from there?

Answer 9

NO

Trunk –> abdominopelvic splanchnic nn (diff. types) –> prevertebral ganglion –> SYNAPSE HERE –> abdominal viscera via periarterial extensions of plexuses (run w/ aa.)

Question 10

What are the different abdominopelvic splanchnic nn. that the sympathetic fibers can go into after leaving the paravertebral trunk?

Answer 10

Lower thoracic splanchnic nn. (greater, lesser, least splanchnic nn.)

Lumbar splanchnic nn. (from lumbar sympathetic trunks)

Question 11

Pre-synaptic parasympathetic fibers to foregut and midgut GI autonomics get there how?

Answer 11

Via anterior and posterior vagal trunks –> enteric/intrinsic ganglia on/near organ –> SYNAPSES –> one of the enteric plexuses

Question 12

Pre-synaptic parasympathetic fibers to hindgut GI autonomics get there how?

Answer 12

Pelvic splanchnic nn. –> intrinsic/enteric ganglia –> organ

Question 13

SO, the vagus nerve does parasympathetic innervation UP TO what point?

Then what takes over?

Answer 13

Left colic flexure

Pelvic splanchnic nn.

Question 14

Intrinsic/enteric plexuses w/in the GI tract that the sympathetic/parasympathetic nerves can go to (w/ common names)

Answer 14

Myenteric plexus (Auerbach)

Submucosal plexus (Meissner)

Question 15

Location and function of each of the 2 intrinsic/enteric plexuses

Answer 15

Myenteric - btwn longitudinal and circular m. layers - motility

Submucosal - in submucosa - secretions, blood flow, absorption

Question 16

The splenic a. and v. are contained w/in what?

Answer 16

Splenorenal ligament

Question 17

3 main plexuses that are associated with major arteries

Answer 17

Celiac plexus

Superior mesenteric plexus

Inferior mesenteric plexus

Question 18

Where do the 3 plexuses associated w/ major arteries come into the scheme of autonomic innervation for GI?

Answer 18

Connected networks of nerves that are thoroughfares for splanchnic nn., etc. going to different locations w/in the GI tract

SO helping the nerves get to where they need to go

Question 19

Sympathetic and parasympathetic fibers in the celiac plexus

Answer 19

S: greater and lesser splanchnic nn.

P: Posterior vagal trunk (L and R vagus nn.)

Question 20

SO, in the sympathetic pathway for GI innervation, the celiac plexus is between what two “stops”?

Answer 20

Paravertebral trunk and prevertebral trunk

Question 21

SO, a parasympathetic AP going through the celiac plexus to its end organ must be using what nerve to get there?

Answer 21

Posterior vagal trunk

Question 22

Sympathetic and parasympathetic fibers in the superior mesenteric plexus

Answer 22

S: Periarterial extensions of the plexus that follow branches of the SMA from the prevertebral ganglia, which came from lesser and least splanchnic nn.

P: Root of vagus n. from celiac plexus –> periarterial extensions along SMA branches –> enteric ganglia

Question 23

SO, to innervate the areas of the SMA, sympathetics get there how?

Answer 23

Via lesser and lease splanchnic nn. –> prevertebral ganglia –> periarterial extensions of the superior mesenteric plexus –> organ

Question 24

SO, to innervate the areas of the SMA, parasympathetics would have to get there how?

Answer 24

Via vagus n. through celiac plexus to the superior mesenteric plexus, then out along the SMA branches to the enteric ganglia on the GI tract

Question 25

Sympathetic and parasympathetic fibers in the inferior mesenteric plexus

Answer 25

S: lateral roots from lumbar sympathetic trunk

P: medial root of vagus n. from superior mesenteric plexus

Question 26

What is Calot’s Triangle?

What sits within it?

Answer 26

Area below the liver between cystic duct and common hepatic duct

Cystic artery

Question 27

Cholecystectomy

How to do it?

Answer 27

Gall bladder removal

Cut cystic duct and cystic a., then release it from fascia/liver

Question 28

If the liver is bleeding, how do you stop it from spreading?

Answer 28

Pringle maneuver - clamp the hepatoduodenal ligament

Question 29

Portal vein is made from what veins?

Contains what?

Answer 29

Splenic + SMV (+ IMV)

Nutrient-rich, O2-poor blood

Question 30

Blood supply to pancreas

Answer 30

Celiac - superior pancreaticoduodenal

SMA - inferior pancreaticoduodenal

Question 31

The SMA supplies organs from what embryological region?

Answer 31

Midgut

Question 32

Branches of the ileocolic a.

Answer 32

Ileal br.'s
Appendicular br.
Colic br.
Cecal br.'s
Marginal a.

Question 33

Does the SMV have the same or different branches as the SMA?

Goes to where?

Answer 33

SAME

Portal v.

Question 34

The IMA supplies organs of what embryologic region?

Answer 34

Hindgut

Question 35

Importance of Sudeck’s Critical Point?

Answer 35

Must maintain arteries here during colorectal surgery

Cutting one –> ischemic bowel

Question 36

Do the branches of the IMV follow those of the IMA?

Go where ultimately?

Answer 36

NO

Portal v.

Question 37

3 sets of rectal vessels (w/ origins)

Answer 37

Superior rectal (IMA)

Middle rectal (internal iliac)

Inferior rectal (internal pudendal)

Question 38

Where do rectal aa. anastamose?

Answer 38

W/in the walls of the rectum and anus

Question 39

4 causes of ischemic bowel

Answer 39

Embolus
Arterial thrombosis
Venous thrombosis
Volvulus (kink in sigmoid colon)

Question 40

Why is the sigmoid colon most likely to form a volvulus?

Answer 40

Has no mesentery, so can twist around easier

Question 41

2 types of abdominal pain

Answer 41

Somatic

Visceral

Question 42

Somatic abdominal pain arises from where?

Nerves involved?

Signals go where?

Answer 42

Skin, fascia, muscles, parietal peritoneum

Phrenic, intercostal, thoracic, lumbar, obturator

To CNS

Question 43

Visceral abdominal pain arises from where?

Nerves involved?

Signals go where?

Answer 43

Organs, visceral peritoneum, mesenteries

Afferent nn. –> posterior roots

To CNS

Question 44

Causes of visceral pain

Answer 44

Ischemia, stretching, obstruction

Question 45

Example of somatic referred pain

Answer 45

Pleurisy (inflammation of lung pleura) –> chest pain

Question 46

Example of visceral referred pain

Answer 46

Appendix

Pain in umbilical area